Final answer:
The most appropriate format for designing a transparent graphic for print in InDesign is a high-resolution file without background, saved as a Photoshop PSD file.
Step-by-step explanation:
When designing a transparent graphic that needs to be imported into InDesign for printing, the most appropriate format is to maintain a high resolution file without the background and save the file as a Photoshop file, choosing the PSD format. The PSD format supports transparency and allows for high-quality printing. It's important to ensure the resolution of the file is sufficient for printing; commonly, a resolution of 300 pixels per inch (ppi) is used for print materials. This will ensure that the image maintains clarity and sharpness when printed.
While it may seem tempting to work with lower resolutions, such as 72 ppi, these are intended for screen display rather than print, and will result in poor print quality. The Scitex CT format is generally not necessary for typical graphic design work and can be cumbersome due to its specialized use. Instead, keeping the graphic in PSD format with a transparent background and a high resolution is the best practice for a workflow involving InDesign and subsequent printing.